Joints (a.k.a. Articulations)

I. Introduction A.Joint 1. articulation 1. Also called an articulation 2. Defined: A joint is a point of contact between bones, cartilage and bones, or teeth and bone

I. Introduction B. Function they hold the skeletal bones together Allows the rigid skeleton some flexibility so that gross movements can occur

C. Relationship between Joints and Movements 1. The closer the fit between bones at a joint, the stronger the joint. 2. Strong joints exhibit restricted movements. 3. The greater the distance between articulating bones the greater range of movements

II. Classification A. Based on either 1. S 1. S tructure based on the nature of the material comprising them 2. Function based on degree of movement they allow

II. Classification B. Functional Classifications Synarthroses arthrose=joint, syn=together Immovable jointsImmovable joints Examples: suturesExamples: sutures

Synarthroses

II. Classification C. Functional Classifications Amphiarthroses arthrose=joint, amphi=both Slightly movable joints Between tibia and fibula

Amphiarthroses

II. Classification C. Functional Classifications Diarthroses arthrose=joint, dia=apart a. freely movable joint b. example: knee joint

II. Classification b. no joint cavity C. Structural classifications Fibrous Joints a. joints held together by fibrous connective tissue

SUTURES Bones are held together by a thin layer of dense fibrous tissue and also by interlocking projections of the bones. Found only in the skull

GOMPHOSES a peg-in-socket fibrous joint

Bones are held together by a cord or sheet of dense fibrous connective tissue SYNDESMOSES

II. Classification B. Structural Classifications Cartilaginous Joints a.held together by cartilaginous tissue b. no joint cavity

Synchondroses immovable only hyaline cartilage

SYMPHYSIS VERY limited movement Hyaline and fibrous cartilage

B. Structural Classifications Synovial joints a.held together by a synovial capsule b. Have a joint cavity c. Includes most joints

Gliding Joints Plane (= gliding). Opposite bone surfaces are flat or slightly curved. Only sliding motion in all directions are allowed.

Hinge Joints Convex surface of one bone fits smoothly into concave surface of the second bone.

Pivot Joints A rounded, pointed or conical surface of one bone is inserted into a ring made partly of another bone and partly of a ligament. only movement allowed is the rotation of one bone around its own axis

Ellipsoidal (= condyloid) Joints Oval-shaped surface fits into an oval-shaped cavity

Saddle Joints First bone's articular surface is concave in one direction and convex in the other while the second bone is just the opposite.

Ball and Socket Joints head fits into a cup- shaped depress ion most freely moving of all joints

V. Joints (a.k.a. Articulations) C.Types of Movement in Synovial Joints 1.Gliding slight movementslight movement example: vertebrae 2.Rotation Movement around the long axis of limb Shoulder joint

V. Joints (a.k.a. Articulations) C.Types of Movement in Synovial Joints 3.Angular a. flexion decreasing angle b. extensio n Increasing angle

C. Types of Movement in Synovial Joints C.Angular a. hyperextension extension beyond anatomical position b. circumduction limb movement with limb describing a cone

V. Joints (a.k.a. Articulations) C.Types of Movement in Synovial Joints 3.Angular abduction d. abduction movement away from midline e. adduction e. adduction toward midline

C.Types of Movement in Synovial Joints 4.Rotation turns right to left

4. Rotation a. a. pronation turns wrist so palm is facing dorsally b. supination b. supination palm turned anteriorly C. Types of Movement in Synovial Joints

5. Special Cases a. a. plantar flexion and dorsiflexion b. dorsiflexion C. Types of Movement in Synovial Joints